Hi Melody847,
The better options in the Chicago area I’m aware of are listed in posts #2 and #4 here.
Quality Sleep / My Green Mattress uses Talalay latex but RoomandBoard has Dunlop latex mattresses if that’s what you are specifically looking for.
Ikea in Bolingbrook and Schaumburg also has a Dunlop latex mattress that uses 85% natural dunlop latex (the Edsele).
http://www.northshorebedding.com/Organic_Mattresses.html also carries a range of Dunlop latex mattresses as well. While they won’t be inside your budget range they will give you a chance to test a range of Dunlop latex mattresses.
It may also be worthwhile looking at some of the online options that are available to you as well that are listed in post #21 here.
Phoenix